Three-component developer photographic processing monobath composition and method

ABSTRACT

AN IMPROVED COMBINED DEVELOPER-FIXER MONOBATH PHOTOGRAPHIC PROCESSING COMPOSITION, AND METHOD OF USE THEREFOR, POSSESSING SHORT PROCESSING TIME, STABILITY AND EXTENDED PERIOD OF ACTIVITY WHILE PRODUCING FINE GRAIN, GOOD QUALITY IMAGES INCLUDING A DEVELOPER WHICH COMBINES THREE DEVELOPING AGENTS. BY COMBINING MONOBATH COMPONENTS IN ACCORDANCE WITH A BASIC FORMULA MONOBATHS HAVING WIDE GENERAL APPLICABILITY FOR OPTIMUM PHOTOGRAPHIC PROCESSING OF VARIOUS SILVER HALIDE FILM AND PAPER TYPES IN DIVERSE PROCESSES AND APPARATUS ARE OBTAINED.

United States Patent 3,806,344 THREE COMPONENT DEVELOPER PHOTO- GRAPHIC PROCESSING MONOBATH COM- POSITION AND METHOD Daniel Earle Speers, Southport, Conn., assignor to General Film Development Corporation, Southport, Conn. No Drawing. Filed Mar. 31, 1972, Ser. No. 240,275 Int. Cl. G03c 5/38, 5/30 US. Cl. 96-61 M 7 Claims ABSTRACT OF THE DISCLOSURE An improved combined developer-fixer monobath photographic processing composition, and method of use therefor, possessing short processing time, stability and extended period of activity while producing fine grain, good quality images including a developer which combines three developing agents. By combining monobath components in accordance with a basic formula monobaths having wide general applicability for optimum photographic processing of various silver halide film and paper types in diverse processes and apparatuses are obtained.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to combined developer-fixer photographic processing compositions, commonly known as monobaths, for black and white or monochrome silver halide emulsion films and papers, and more particularly, to monobath compositions producing fine grain, good quality images within a short processing time.

Monobaths eliminate the conventional three-step photographic processing cycle that involves a developing bath, a stop bath, and a fixing bath by accomplishing the development process of reducing silver halide to metallic silver as well as the fixing process of rendering remaining 'silver salts water soluble, by combination with certain chemical compounds, in a single solution. However, a monobath is much more than a simple combination of a developer and a fixer and involves complex chemistry. Typically, monobaths are a composite solution of a solvent, usually water, a developing agent, a preservative, alkali for activation or acceleration, a restrainer or antifoggant and a fixing agent. Special purpose compounds are also occasionally added.

Description of the prior art A monobath, to be successful, must not only reduce the number of solutions in the photographic processing cycle to one complex solution, but must also maintain full emulsion speed, normal contrast and image density, normal graininess, a low fog level, and also provide a reasonably short processing time. The gamma value of a monobath is fixed by the chemical composition and monobath processing times are related more to clearing time than to development time. With development to a fixed gamma proceeding to completion at a set rate at the same time fixation proceeds, the developing action must be rapid enough to overcome the concurrent fixation process or the concentration of fixing agent must be high enough to insure complete clearing of the films unexposed silver halide.

Prior art monobath formulations possess serious shortcomings which limit their acceptance for general photographic processing. Thus, rapid processing has often been obtained largely by compromising other desirable properties. Monobaths seeking to control the course of develop ment by the addition of caustic alkali to accelerate the activity of the developing agent have produced highly active, high speed developers which act at the expense of causing graininess. Fast action has often been accompan- 3,806,344 Patented Apr. 23, 1974 r. CC

ied by undesirable side effects such as unacceptable image graininess or emulsion softening. Further disadvantages of prior art monobaths include an undesirably rapid chemical degradation of the solution resulting in short shelf life and curtailment of the effect of and processing life of a used monobath, often due to the deposition of a silver sediment of the used solution. Monobaths seeking to overcome the aforementioned problems and shortcomings have largely been limited to special purposes and have a high specificity of bath for a single or very restricted number of photographic products or processes. A comprehensive discussion of monobaths, including representative formulations, is presented in Monobath Manual, Grant Haist, Morgan & Morgan, Inc., Hastings on Hudson, NY. 1966) The monobath compositions of this invention exhibit a short processing time while producing fine grain, good quality images without sacrifice or compromise of desired properties. Moreover, the combined developer-fixer monobath composition solutions of this invention are stable, retain their activity over a long period of time, and have a wide applicability for photographic processing.

SUMMARY OF THE INVENTION The present invention provides an improved combined developer-fixer monobath photographic procesing composition possessing short processing time, stability and extended period of activity while producing fine grain, good quality images by including therein a developer which is a combination of at least three different developing agents. By combining 'various monobath components in accordance with a basic formula keyed to the first developing agent, monobaths are prepared having wide general applicability for optimum photographic processing of various film and paper types in diverse processes and apparatuses.

Accordingly, it is an object of this invention to provide a monobath composition which will enable photographic processing in a short time while producing fine grain, good quality images.

A further object is the provision of a monobath composition which will remain stable, possess a long shelf life and retain its activity after use over a long period of time.

An additional object of this invention is the provision of a composite solution of multiple developing agents to provide a monobath capable of rendering good contrast and density, substantially free from dichroic fog and with no more development fog than is customarily obtained with ordinary developing and fixing procedures.

A yet further object of this invention is the provision of a monobath composition which has wide general applicability for photographic processing of many kinds of photo products such as differing silver halide film and paper types in various processing procedures and methods using difierent apparatus and processing equipment, and which is usable over wide temperature and time ranges.

Another object is the provision of a method which will enable photographic processing of silver halide emulsion films in a relatively short time by using a combined developer-fixer monobath solution exhibiting rapid development activity while producing fine grain, good quality images and possessing an extended activity life.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In my co-pending patent application Ser. No. 233,787, filed Mar. 10, 1972, for Fine Grain, High Speed Photographic Processing Monobath Composition & Method I describe generally the photographic processing behavior of a monobath composition and the dependence of improved characteristics and behavior of a monobath upon the total composition of a solution rather than upon the individual components. The reader is referred thereto, and those general observations are incorporated herein by reference, for background information which will be of assistance in understanding the present improved monobath composition invention.

In simple developer compounds, an energetic developer produces a heavy density at the film surface, While a less energetic developer might produce an equal density only when sufiicient time had elapsed for the developer to penetrate into the silver halide emulsion layers. Some developers have little or no induction period, while others require an induction period prior to any significant development activity. Some developers are fast working but produce less contrast than developers which are slow Working but capable of producing heavy density.

I have discovered that I can selectively control the energy and speed of development as well as the final silver density by combining certain developing agents in a specific manner. Particularly, I have found that when three preselected developing agents are used together, a -super-additive effect is obtained, so that the sum of their combined actions is greater than the sum of their actions when used alone, to yield a monobath composition exhibiting a more rapid penetration of the potential barrier surrounding silver halide grains and, thus, faster development activity as well as a balancing of low and high density and contrast.

- it is my theory, although I do not wish to be bound thereby since my invention is fully illustrated by the specific embodiments set forth in the examples following, that a negative charge potential field surrounding each hilver halide grain forms an electrostatic bannier or threshold shell which inhibits many developing agents from reaching the grains and also affects uniform penetration of the emulsion. The time required for the developing agent to reach the grain is an induction period proportional to the magnitude of the charge of the developing agent. As the magnitude of the charge barrier surrounding the silver halide grain is reduced, more developing agent reaches this surface and the previously irregular penetration of the emulsion by the agent, due to concentration ditference driving forces acting substantially alone, becomes uniform. The initial rate of reaction of developing 'agents having a large induction period is relatively slow but increases as the magnitude of the charge decreases.

Developing agents such 1,4-dihydroxy-benzene (commonly referred to as hydroquinone) and 2-chloro-l,4-dihydroxy-benzene (commonly referred to as chlorohydroquinone) have two negative charges in working solution and a greater induction period with the result that they react quite slowly until the initial density is reached. Thereafter, the density is proportionate to the development time and can result in high contrast.

' Developing agents such as l-phenyl-3-pyrazolidone (commonly referred to as phenidone) and l,2-dihydroxybenzene (commonly referred to as catechol) have a single negative charges. The preferred composite developer coninduction period than developers with two negative charges. Development is proportionate to the developing time although there is less contrast and density than with developers having longer induction periods.

I There are also developing agents such as 1,4-diaminobenzene (commonly referred to as para-phenylene diamine), cevitamic acid (commonly referred to as ascorbic acid or Vitamin C) and 1-hydroxy-4-methyl-aminobenzene (commonly referred to as para-methylaminophenol or metol, which is the sulphate salt thereof) which have no negative charge in working solution and therefore no induction period and begin to react immediately. However, they produce very little density and extremely low contrast.

The developer component of my improved monobath composition contains three developing agents. The first developing agent is selected from that group of developing agents possessing two negative charges, the second developing agent is selected from that group of developing agents possessing one or no negative charge, while the third developing agent can be selected from that group of developing agents having either two, one or no negative charges. The preferred composite developer contains one developing agent from each group so that there is present one having two negative charges, one having one negative charge and one having no negative charge whatsoever. It is my belief that the developing agents with no or one negative charge attack or alter the electrostatic potential barrier surrounding each grain in a way to reduce its barrier action so as to permit it to be acted upon and penetrated rapidly. Once this has beendone, the developing agent with two negative charges can then also uniformly penetrate the emulsion and take over.

I have found that varying the amounts of developing agents selected from the different groups controls both the induction period and the final density and contrast. When combined in a monobath, these developing agents produce a composition capable of a very exact fixed gamma and a remarkable degree of reproducibility. Appropriate selection of the other constituents in the combination in the monobath results in a formulation which produces a highly refined fixed development to a fixed gamma over a wide range of temperature and dilution. I also observed that the chemical combination of multiple developing agents reinforced regeneration of reaction products during the reduction of exposed silver halide as well as resulting in the formation of reaction products which accelerate development. These intermediate products apparently have a positive charge which very effectively reduces the barrier effect or threshold action of the electrostatic potential field.

The following examples illustrate formulations of specific embodiments of the monobath compositions of this invention.

The formulation of Example 1 provides a fine grain, high qualtity monobath designed to produce medium to high contrast black and white film and is particularly suited to F film and some instrumentation film types. It is usable with films such as those commercially available under the trademarks Kodak Plus-X, Tri-X, and Panatomic-X, Ansco Super Hypan, Ilford HB3, and Agfa ISU, ISS, and IFF. Film should be developed six minutes in the above solution for the first roll, and thirty seconds thereafter for each additional roll.

EXAMPLE 2 Material: Amount Water "ml-.. 2000 Anhydrous sodium sulphite g 210 Hydroquinone g 24 Sodium carbonate g 4.8 Ascorbic acid g 3.36 Sodium hydroxide g 8.2 Phenidone g 1.92 Potassium bromide g 1.47 Sodium thiosulphate g -300 The above formulation is also suitable for S & M films by adjusting the sodium thiosulphate content and by extending development time.

EXAMPLE 3 Material: Amount Water ml 2000 Anhydrous sodium sulphite g 210 Hydroquinone g 28 Sodium carbonate g.. 9.4 Ascorbic acid g 2.84 Sodium hydroxide ..g 12.5 Phenidone g 3.3 Potassium bromide g 1.47 Sodiom thiosulphate g 180-280 The above formulation results in a medium contrast high quality monobath which produces fine grain negative film and is particularly suited to do those films specifically The above formulation produces a highly satisfactory long life, medium contrast monobath.

The monobath formulations of Examples 1 through 4 may have added thereto, as an option, 1 gram benzotriazole as an anti-foggant, and a dye, bromothymol blue solution, three milliliters as a visual pH indicator. Moreover, I have found the monobath formulations of Examples 1 through 4 well suited for the incorporation therein of the additive disclosed in my copending patent application Ser. No. 228,393, filed Feb. 22, 1972 for Composition and Method for Increasing Speed and Stability of Photographic Processing Monobaths. That additive solution may comprise 1000 milliliters water, 1 to 100 grams anhydrous sodium sulphite, .5 to 2 grams phenosafranin, and 50 to 150 grams or milliliters of a cationic surfaceactive agent of the quaternary type. The reader is referred to the specification of Ser. No. 228,393 which is specifically incorporated herein by reference, for more detail thereof. Approximately 5 milliliters of such addition in the formulations of Examples 1 through 4 have shown excellent results.

A representative formulation of the combined trideveloper-fixer photographic processing monobath solution of this invention may be considered as comprising to 35 grams 1,4-dihydroxy-benzene, cevitamic (ascorbic) acid in an amount of 12 to 17 weight percent of the amount of 1,4-dihydroxy-benzene, 1-phenyl-3-pyrazolidone in an amount of 6 to 12 weight percent of the combined amount of 1,4-dihydroxy-benzene and cevitamic (ascorbic) acid, sodium carbonate in an amount of 18 to 22 weight percent of the amount of l,4-dihydroxy-benzene, sodium hydroxide in an amount of 32 to 5 2 weight percent of the combined amount of 1,4-dihydroxy-benzene and cevitamic (ascorbic) acid, potassium bromide in an amount of 1 to 7.5 weight percent of the combined amount of 1,4-dihydroxy-benzene, cevitamic (ascorbic) acid and l-phenyl 3 pyrazolidone, sodium thiosulphate in an amount of 600 to 1200 weight percent of the combined amount of 1,4-dihydroxy-benzene, cevitamic (ascorbic) acid and *l-phenyl-3-pyrazolidone, anhydrous sodium sulphite at least in excess of 200 grams and 2000 milliliters water, as well as the aforementioned additive solution.

The compositions set forth in Examples 1 through 4 are of working strength solutions and may be used by bringing therein contact with silver halide emulsion films under the usual conditions. The formulation of Example 1 has also been found excellent for producing quick proofs on Hefa-3 bromide paper. The recommended processing temperature is 75 F. and normal temperature variation does not appreciably affect the results. However, if it is necessary to use the formulations at high temperatures, modifications may be made. Thus, at temperatures above 105 F., 15 grams sodium sulphate and 0.01 grams benzotriazole should be added for each 10 F. increase in temperature. However, the stability and keeping properties of formulations s0 modified may not be as good as the original. When sodium hydroxide is present and a chemical fog is evident, the amount of caustic alkali must be reduced. Potassium hydroxide or other generally acceptable alkali metal hydroxides may be used in the formulations in place of or in addition to sodium hydroxide.

Monobaths give the best results within a pH range of 11 to 12. If any formulation shows a measured range below this and greater density is desired, the pH can be adjusted with the addition of caustic alkali. However, if long storage life is required addition of sodium carbonate or potassium carbonate is more desirable than sodium hydroxide. Trisodiumphosphate, sodium metaborate and sodium metasilicate in small amounts have been used successfully.

The stability of monobaths and the rate of exhaustion may be improved by adding potassium alum to the formulations in the amount of 20 grams per liter of water. However, care must be taken to assure that the alum properly goes into solution and does not affect the other components. In place of alum, and especially if the negative emulsion displays signs of softening, a solution of 38% formaldehyde can be added in the amount of 10 milliliters per liter of water.

Monobath exhaustion can be significantly reduced by a system of replenishment generally to the extent of cutting the rate of exhaustion in half. The typical exhaustion rate is 2 ounces per square inches of surface area treated. Variations will occur depending on the thickness and type of emulsion as well as on wether or not the film is processed at once rather than over a period of time with several hours or days occurring between processing times. Generally, X-ray plates consume more solution than do medium speed instrumentation and amateur film while microfilm capacity is almost four times as great. The capacity of the monobath can be doubled. For example, a pint of solution normally processes 8 rolls of 35 millimeter instrumentation film; after processing one roll of film, first pour one ounce milliliter of fresh solution into an empty solution storage bottle and then return enough used developer to the bottle to bring the volume up to its original level of 16 ounces and discard the excess. Sludge or other foreign matter accumulating in the monobath may be removed by filtration. The solution should be discarded after processing 16 rolls.

The variation due to time or temperature changes is not great since the gamma value of the monobath is fixed by its composition. The optimum processing time will be readily ascertainable from observation by those skilled in the art. A wide gamma range can be had by varying the amount of sodium thiosulphate in the formula. Other known fixing agents such as ammonium, potassium, sodium thiocyanate or thiosulphate may be used. Care should be taken to avoid having an excess; however, for the film will begin to turn brown. This may be corrected by dilution with water to which grams anhydrous sodium sulphite per liter has been added. All constituents set forth herein are commercially available and the photographic grade should be used unless other grades have been tested for the required degree of purity and found satisfactory. The water used should be distilled, and preferably deionized, water.

Subsequent to processing in the monobath, the keeping properties of the film may be improved by a first washing in water to which a weak acid such as boric or acetic acid has been added. This serves to neutralize the alkali of the monobath.

Because of their general wide applicability for various silver halide film and paper types the monobath compositions of this invention are highly suitable for diiferent processing methods and equipment. Thus, the monobaths find use in home darkrooms as well as in professional and commercial applications. This is due not only to the improved properties in the image obtained but also the convenience of use. For example, in commercial machine processing where film is passed essentially continuously or intermittently through monobath, wash, and dry tanks use of the monobaths of this invention results in considerable savings in time and eifort and thus greater economy by enabling the same monobath solution tobe used for various film types. Thus, Where one machine must be utilized to process, at various frequent but intermittent times, instrumentation film, then X-ray film and then microfilm there is no need to interrupt operation to Wash the tanks and change solution after each film operation when using this general use monobath.

Thus, improved monobath compositions having short processing time and an extended development activity for producing fine grain and good image quality for a variety of films and papers with different processing techniques and equipment have been provided according to this invention. A method of photographic processing silver halide emulsions and prints using these improved monobath compositions has also been provided.

I claim:

1. An improved combined developer-fixer photographic processing monobath solution possessing short processing time, stability and extended period of activity while producing fine grain, good quality images in silver halide emulsion films and papers when used at a processing temperature of approximately 75 F. and at a pH range of 11-12 comprising 20 to 35 grams of a first developing agent selected from the group consisting of 1,4-dihydroxybenzene and halogen derivatives of 1,4-dihydroxy-benzene, a second developing agent, present in an amount of 12 to 17 percent of the weight of the first developing agent, selected from the group consisting of ascorbic acid, 1- hydroxy-4-methyl-aminobenzene and 1,4-diaminobenzene, and a third developing agent, present in an amount of 6 to 12 percent of the combined Weight of the first and second developing agents, selected from the group consisting of l-phenyl-3-pyrazolidone and 1,2-dihydroxy-benzene and a fixing agent selected from the group consisting of thiocyanate and thiosulphate salts of compounds selected from the group consisting of ammonium, potassium and sodium in an amount of 6 to 12 times the combined weight of all three developing agents for use in Water solvent in a working strength solution.

2. A combined developer-fixer photographic processing monobath solution as claimed in claim 1 further comprising an alkali metal hydroxide in an amount of 32 to 52 percent of the combined weight of the first and second developing agents.

3. A combined developer-fixer photographic processing monobath solution as claimed in claim 1 further comprising an alkali metal carbonate in an amount of 18 to 22 percent of the Weight of the first developing agent.

4. A combined developer-fixer photographic processing monobath solution as claimed in claim 1 further comprising potassium halide in an amount of 1 to 7.5 percent of the combined weight of all three developing agents.

5. An improved combined developer-fixer photographic processing solution possessing short processing time, stability and extended period of activity while producing fine grain, good quality images in silver halide emulsion films and papers comprising 20 to 35 grams 1,4-dihydroxybenzene, ascorbic acid in an amount of 12 to 17 weight percent of the amount of 1,4-dihydroxy-benzene, l-phenyl- 3-pyrazolidone in an amount of 6 to 12 Weight percent of the combined amount of 1,4-dihydroxy-benzene and ascorbic acid, sodium carbonate in an amount of 18 to 22 weight percent of the amount of 1,4-dihydroxy-benzene, sodium hydroxide in an amount of 32 to 52 weight percent of the combined amount of 1,4-dihydroxy-benzene and ascorbic acid, potassium bromide in an amount of 1 to 7.5 weight percent of the combined amount of 1,4 dihydroxy-benzene, ascorbic acid and 1-pheny1-3-pyrazolidone, sodium thiosulphate in an amount of 600 to 1200 weight percent of the combined amount of 1,4-dihydroxybenzene, ascorbic acid and 1-phenyl-3-pyrazolid0ne, anhydrous sodium sulphite at least in excess of 200 grams and 2000 milliliters water.

6. A combined developer-fixer photographic processing monobath solution as claimed in claim 5 further comprising five milliliters of an additive solution comprising 1000 milliliters water, 1 to grams anhydrous sodium sulphite, .5 to 2 grams phenosafranin and 50 to grams cationic surface-active agent of the quaternary type.

7. A method of photographically processing silver halide emulsion films comprising immersing the film for approximately six minutes in a monobath solution having a pH of 11-12 and a temperature of approximately 75 F. comprising in combination, 20 to 35 grams 1,4-dihydroxy-benzene, ascorbic acid in an amount of 12 to 17 weight percent of the amount of 1,4-dihydroxy-benzene, 1-phenyl-3-pyrazolidone in an amount of 6 to 12 weight percent of the combined amount of 1,4-dihydroxy-benzene and ascorbic acid, sodium carbonate in an amount of 18 to 22 weight percent of the amount of 1,4-dihydroxy-benzene, sodium hydroxide in an amount of 32 to 52 weight percent of the combined amount of 1,4-dihydroxy-benzene and ascorbic acid, potassium bromide in an amount of 1 to 7.5 weight percent of the combined amount of 1,4- dihydroxy-benzene, ascorbic acid and 1-phenyl-3-pyrazolidone, sodium thiosulphate in an amount of 600 to 1200 weight percent of the combined amount of 1,4-dihydroxybenzene, ascorbic acid and l-phenyl-3-pyrazolidone, anhydrous sodium sulphite at least in excess of 200 grams and 2000 milliliters Water and washing the film in water to which has been added a Weak acid selected from the group consisting of boric and acetic for a length of time suflicient to neutralize the alkali of the monobath.

References Cited UNITED STATES PATENTS 3,178,282 4/1965 Luckey et al 96-66 R 3,240,603 3/ 1966 Schiiler 96-66 R 3,615,513 10/1971 Haist et a1 96-61 M FOREIGN PATENTS 558,129 6/1958 Canada 96-61 M OTHER REFERENCES British Journal of Photography, Jan. 27, 1961, pp. 38- 41 and 49, by Crawley.

Monobath Manual, Haist, 1966, pp. 19-44, 46-47.

NORMAN G. TORCHIN, Primary Examiner M. F. KELLEY, Assistant Examiner US. Cl. X.R. 9666.3 

